Caption Group
Daniel J. Field

110. European Black Tern, Dernford Farm Reservoir, Cambridgeshire, May 2022; and 111. American Black Tern, Long Nanny, June 2022. As described in Olsen & Larsson (1995), the black of the head of American Black Tern extends down onto the mantle, but there is a better-defined transition between the black head and grey mantle in European Black Tern. As in juveniles, the rump and uppertail-coverts are darker on American Black Tern than on European Black Tern.

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